High intensity light sources, and particularly white high intensity light sources, are interesting for various applications including spots, stage-lighting, automotive lighting and digital light projection. For such purposes, as well as for obtaining a desired light shape, light distribution and color distribution with a point of high intensity, it is possible to make use of so-called light concentrators where short wavelength light is converted to longer wavelengths in a highly transparent luminescent material. Such a transparent luminescent material is illuminated by LEDs to produce longer wavelengths within the luminescent material. Converted light, which will be waveguided in the luminescent material, is extracted from a surface leading to a point of high brightness.
Document WO 2012/056382 A1 describes in one embodiment a light emitting device comprising a waveguide, a light source and a plurality of light outcoupling structures. The waveguide may be provided with a luminescent material arranged on or in the waveguide and may thereby be configured to convert light from a light source into luminescent material emission.
However, in various lighting applications such as automotive lighting a complicated light shape, light distribution and color distribution is needed. For instance, when illuminating a road it is necessary to have a light beam which must have a particular shape and also have a particular intensity distribution. Furthermore, there are applications, such as headlamps, where more complicated angular light color distribution is needed for comfort and safety. For example, for automotive lamps, it may be desired that in the straight forward direction light is white for good visibility, in the left (or right) direction more yellowish light may be preferred to avoid the blinding of oncoming drivers and in the right (or left) direction more bluish light may be preferred in order to enhance the visibility of the road marks. This is very difficult to obtain in a simple way by using known light emitting devices, particularly when employing LEDs.